This insults my Sudoku abilities.
First off, it was way too easy. Second of all, I reached a point where only 4 blank boxes remained, shared by two rows, two columns and two boxes. Each incomplete row, column and box was lacking a 4 and a 9. That meant that I could (theoretically) fill in the numbers as follows (ignore periods):
4.9
9.4
or
9.4
4.9
Both permutations would be correct, because the use of either would complete the puzzle with the numbers 1-9 in every row, column and box. So I put one in, and it was determined to be incorrect. I put the other one in, and it was correct. So I realized that this game is not programmed to detect repeat numbers in any particular row, column, or box, but instead looked to see if numbers matched a single solution, even though that particular solution was not the only correct one.
There are a couple other things I do not like about this game, but I'm getting tired. Trust me, it's an affront on all serious Sudoku players.